Reasonable character limit for a comment field on a site feedback form?

Question

I have a simple feedback form (see screenshot) on each page on a site. The user has to select whether the page was helpful or not (radio buttons yes/no) and there is also a text area input where the user can add extra information about how we could improve the page.

Would you recommend I have a character limit on this field (i've seen it done on other sites that are similar to mine) and if so, what would be a reasonable character limit to set?

N.b. I can't find a similar question about character limits on feedback/comment fields so please edit if there is a similar question already posted (I'm surprised I can't find one).

Answer 1

According to w3.org - http://www.w3.org/MarkUp/html3/textarea.html :-

Note: In the initial design for forms, multi-line text fields were supported by the INPUT element with TYPE=TEXT. Unfortunately, this causes problems for fields with long text values as SGML limits the length of attribute literals. The HTML 2.0 DTD allows for up to 1024 characters (the SGML default is only 240 characters).

So perhaps limit it to 1024 characters?

EDIT:

Actually, this is a very interesting question(!) as I believe this was probably introduced at this point for memory reasons ( believe this to be 1Kb if a character is 1byte(?) but I can't seem to find if this limit has ever been increased! It seems resonable that this should have been - so will have a further look.